Electrode-holder for emission spectrograph

ABSTRACT

In order to permit very accurate centering of electrodes which are intended to support samples for the purpose of spectrometric analysis, the invention provides an electrode holder comprising a column which is adapted to slide within the wall of an excitation chamber. The column is connected on one side of the wall to two end pieces which are each adapted to support a half clamp and on the other side of the same wall to a system for carrying out the displacement of the column in three directions at right angles to each other.

Unite States atent Inventors Alain Heres l0 Toules Aures, 4 Manosque; Alfred Simenauer, Villa n 28 le Petlt, Nice 13 Aix en Provence. both of France Appl. No. 32,898 Filed Apr. 29, 1970 Patented Nov. 9, 1971 Priority May 9, 1969 France 6915076 ELECTRODE-HOLDER FOR EMISSION SPECTROGRAPH 5 Claims, 5 Drawing Figs.

U.S. Cl... 356/86 lnt.Cl G0lj 3/02 Field of Search. 356/86 [56] References Cited UNITED STATES PATENTS 2,346,512 4/l944 Scribner etal 356/86 X Primary Examiner-Ronald L. Wibert Assistant Examiner-F. L. Evans AllurneyCameron, Kerkam 8L Sutton ABSTRACT: In order to permit very accurate centering of electrodes which are intended to support samples for the purpose of spectrometric analysis, the invention provides an electrode holder comprising a column which is adapted to slide within the wall of an excitation chamber. The column is connected on one side of the wall to two end pieces which are each adapted to support a half clamp and on the other side of the same wall to a system for carrying out the displacement of the column in three directions at right angles to each other.

PATENTEDRBV 919m SHEET 1 OF 4 FIG. I

PATENTEDNUY 919m SHEET u or 4 FIG. 5

ELECTRODE-HOLDER FOR EMISSION SPECTROGRAPH This invention relates to an electrode holder for supporting samples which are subjected to electric excitation in order to perform analysis by emission spectrography. According to customary practice, samples of this type are in fact placed in or on prefabricated electrodes which are excited by an electric arc or a high-voltage spark.

It is therefore necessary to ensure that these electrodes are accurately centered with respect to each other and with respect to the optical axis of the spectrograph or in other words that they should be placed in an electrode holder which permits strictly accurate centering.

However, the field of application of an electrode holder of this type must not be limited to any one type of electrode and must permit:

the use of electrodes having different diameters without impairing the quality of electric contact and of positioning,

easy demounting of electrode holder clamps so as to permit cleaning andyor decontamination of these latter after operation and resultant excitation of corrosive or hazardous samples,

modification of said clamps to permit the use of special devices such as devices for the analysis of solid samples or liquid samples,

cooling of the clamps during production of the electric are or sufficient insulation at the time of production of a highvoltage spark.

A number of devices for supporting electrodes are at present available commercially but they fail to meet all these requirements. In fact, perfect centering of electrodes can be obtained by means of these devices only with difficulty by reason of the limited possibilities of adjustment which they afford; the geometry and arrangement of their clamps make it difficult to ensure effective cleaning. Furthermore, these devices are frequently intended to be employed for specific analyses or samples and are not readily suited to other types of analysis.

The present invention is intended to overcome these drawbacks and to satisfy all the requirements mentioned in the foregoing.

This invention is directed to an electrode holder for an emission spectrograph which essentially comprises a cylindrical excitation chamber, at least one of the top and bottom end walls of which is traversed by a sliding column for supporting an electrode-holding clamp within the interior of the chamber and is adapted to support externally of said chamber a system for controlling the opening and closure of the clamp and the displacement of the column in three directions at right angles to each other.

All the control elements are placed outside the excitation chamber, thereby preventingany danger of either contamination or corrosion of said elements irrespective of the nature of the sample.

According to a further property of the invention, the sliding column is constituted by two coaxial tubes, one tube being stationary and the other being capable of rotational motion, said tubes being each rigidly fixed to an endpiece for supporting a half clamp.

Each electrode, that is to say each sliding column which passes through one of the end walls of the chamber can thus be displaced either vertically so as to permit adjustment of the distance between the electrodes or laterally so as to permit centering of the two electrodes relative to each other as well as their alignment along the optical axis of the spectrograph. Optical systems which are mounted in the wall of the chamber serve to check this centering operation.

Moreover, the design of the clamp in two sections in which one section is movable with respect to the other and capable of opening to a fairly substantial extent permits of ready access for purposes of cleaning or changing the electrode.

A number of additional advantages and properties of the invention will in any case become apparent from the following description of one embodiment which is given by way of nonlimitative example. and illustrated in the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view of an electrode holder;

FIG. 2 is a sectional view taken along line II of FIG. 1;

FIG. 3 is a top view of the electrode holder after removal of the protective casing;

FIG. 4 is a plan view with portions broken away and showing an electrode clamp;

FIG. 5 is a partial longitudinal sectional view of said clamp which is assumed to have been opened at an angle of 180..

The electrode holder comprises essentially (as shown in FIG. 1) an excitation chamber 1 having a cylindrical shape, said chamber being closed at the top and at the bottom by plates 2 and 4 which are preferably detachable. There is fixed on each of these plates a mechanism 6 for actuating a sliding column 7 which passes through the plate 2 or plate 4 respectively and which is adapted to support an electrode-holding clamp within the chamber 1.

As shown in FIG. 2, the cylindrical wall of the chamber has an opening 8 of large size which corresponds, for example, to an angle at the center of 120 and is closed by a door 9. Opening of this door permits of extremely ready access to the interior, that is to say in particular to the electrode-holding clamps.

The internal surface of said door and also of the entire chamber 1 is covered with a detachable lining ll of black plastic material such as, for example, polyethylene filled with carbonblack, tetrafluoroethylene or any similar product.

A port 10 which performs the function of a screen and is formed of darkened and frosted glass, for example, is mounted in the door 9 so as to permit visual control while a second port 13 associated with an electric light bulb 19 is mounted in the cylindrical wall at a point which is diametrically opposite to said port 10 and serves to project onto the screen formed by this latter an erect and enlarged image of the electrodes which is visible from the exterior of the chamber.

As shown in FIGS. 1 and 2, the chamber I is fitted with two diametrically opposite windows l2, 14. In the case of the embodiment which is illustrated, one window 14 is closed by a shutter 16 while the other window 12 has an extension in the form of a sleeve 18 which is adapted to carry a system of lenses 20. Said sleeve is also provided with means for adjusting the depth and orientation of said lenses. A third window 15 is also provided in the wall 1; it is located at the same level as the windows 12 and 14 and at an equal distance from these latter and similarly serves as an optical exit to a spectrograph. As shown in FIG. 2, said third window 15 is closed by a shutter 17.

The same chamber 1 is also fitted with two additional and diametrically opposite ports 24, 25. One port 24 is associated with an electric light bulb 26 while the other port 25 is associated with an object-lens and with a system of mirrors 28, 30 which reflects the image obtained to a screen 32 (shown in FIG. I) on which said image appears erect and enlarged. The axis of said ports 24, 25 is at right angles to the axis of the ports 10 and 13 and their point of intersection is extremely close to the axis of the electrodes.

The column 7 which penetrates into said chamber is constituted by two coaxial tubes 7a and 8b, one tube 7b being capable of rotational motion inside the other tube. Each tube terminates in an endpiece 8a and 8b for supporting a half clamp 34, 36 formed of stainless steel, for example (shown in FIG. 4). There is placed in each half clamp a contact 38, 40 which is formed of graphite or any like-conducting material and has the shape of a prism with a trapezoidal base. One contact 38 has a flat lateral surface and forms a uniform extension of the half clamp 36 while the other contact 40 has a V-shaped notch 42 for centering the electrode. Said electrode is thus held in position between three generator lines.

Each end piece and 8b is provided with recesses 44 which may be three in number, for example, connector-pins being intended to be inserted in said recesses and carried by the half clamps 34 and 36 which are thus readily detachable.

As shown in FIG. 4, some connector-pins 46, two of which are provided in each half clamp, are pierced by an axial duct 48 and permit the flow of a cooling fluid while another connector-pin 47 is formed of metal having good electrical conductivity and serves to conduct the current towards the corresponding electrode.

The tubes 7a and 7b (as shown in FIG. as well as each endpiece 8a and 8b and even the half clamps 34 and 36 are pierced by ducts 64 for the circulation of a cooling fluid. This fluid penetrates at 63 into the top portion of the stationary tube 7a, flows through the endpiece 8a and also through the half clamp 34, is then admitted through a port 61 through which the fluid is permitted to flow irrespective of the angular divergence of the clamp into a duct 67 which is defined by a partition wall 69 formed within the tube 7b. The fluid flows through the movable endpiece 8b and the half clamp 36 so as to return through said tube 7b but on the other side of the partition wall 69 towards the tube 7a and the outlet 65 which is pierced in this latter.

The movable central tube 7b is rigidly fixed outside the chamber 1 and the tube 7a to a nut 50 and to a link-arm 52 (as shown in FIG. 3) for driving said tube in rotation. Said linkarm is in fact connected by means of a cable 54 and a second link-arm 56 to a control knob 58 carried by the wall 60 of a casing 62 which protects the electrode-holder assembly. The central portion of the link-arm S6 is also connected to a spring (not shown) which tends to return said link-arm as well as the cable 54 and the link-arm 52 towards the gripping position of the clamp.

The extent of angular displacement of the clamp is relatively substantial and, although it does not attain 1801 as is shown in FIG. 5 solely for the sake of enhanced clarity of the figure, it can nevertheless attain 45. However, the half clamp 34 remains stationary while only the half clamp 36 is capable of displacement and the centering is not modified by opening and closing operations.

The contacts 38 and 40 can also be provided with suitable dimensions which correspond both to the shape and to the nature of the electrodes to be held.

Each column 7 traverses one of the end walls 2 or 4 of the chamber 1 through an opening 66 (shown in FIG. 1) which permits lateral displacement of said column in two directions at right angles to each other. Said opening is closed in leaktight manner by means of a ring 68 in which the stationary tube 7a is capable of sliding with slight friction. Said ring 68 is in turn permitted to slide with slight friction between two rings, namely a top ring 70 and a bottom ring 71, which are carried by the plate 2 or the plate 6.

Outside the chamber 1, each end wall 2, 4 is adapted to support a mechanism 6 for actuating the column 7. Only one of these mechanisms has been illustrated since the second is similar.

The column 7 is fixed outside said chamber 1 in a carriage block 72 formed of insulating material and adapted to carry a nut in which is engaged a vertical worm screw 74 and this latter is secured against translational motion in a carriage 76. At the top portion 'of said carriage, the worm-screw 74 is rigidly fixed to a bevel-pinion 78 (shown in FIG. 3), said pinion being connected by means of a flexible cable 80 to a handwheel 82 which is carried by the wall 60.

The rotation of said handwheel 82 which is accompanied by the rotation of the flexible cable 80 and worm-screw 74 causes the vertical displacement of the carriage block 72 which is secured against rotational motion by means of two vertical columns (not shown in the figure), said columns being rigidly fixed to the carriage 76. Said column 7 is then displaced relative to the opening 66 and the electrode is either lifted or lowered within the chamber 1.

The carriage 76 itself is supported by a carriage 84 by means of transverse guides 86 and is displaced (as shown in FIG. 3) as a result of the rotation of a worm-screw 88, said worm-screw being secured against translational motion but capable of displacement within a stationary nut which is rigidly fixed to said carriage 76. As in the case of the wormscrew 74, the worm-screw 88 is operated by means of a flexible cable 90 from a handwheel 92 which is mounted in the wall 66.

Rotation of said handwheel and of the worm-screw 88 has the effect of displacing the carriage 76 with respect to the carriage 84 within the interior of a stationary support bracket 94 and also has the effect of displacing the complete sliding column assembly 7 within the opening 66.

In addition, guides 95 are provided at right angles to the guides 86 between the carriage 84 and the support bracket 94. Said carriage 84 is also rigidly fixed to a nut traversed by a worm-screw 96 which passes freely through the support bracket 94 and is driven externally of this latter by means of a bevel-pinion 98, a flexible cable 99 and a handwheel 100.

The rotation of said worm-screw 96 therefore has the effect of displacing the carriage 84 which supports the carriage 76 and this latter moves the carriage block 72 together with the column assembly 7 in a direction at right angles to the direction of displacement of the carriage 76 alone.

It is thus possible to displace the electrode-holding clamp in two perpendicular directions as well as in a vertical plane, thereby greatly facilitating centering of the electrode with respect to the optical axis. The displacements are in any case readily controlled from the exterior by virtue of the screens 32 and 10 which show the position of the clamp.

The manual control system which has just been described can also be replaced by an electric control system or any other system and especially by a control system which makes it possible to associate the movements of the upper and lower columns 7 in order to ensure automatic centering of the two electrodes relative to each other. The V-notch of the stationary half clamp also facilitates control of centering by virtue of the possibility of causing said notch to coincide with the point of intersection of the axes on which are located on the one hand the ports 24 and 25 and on the other hand the ports 10 and 13.

Moreover, a ventilation tube 102 is fitted in the plate 2 at the top of the chamber 1, the inlet of said tube being regulated by means of a butterfly valve 104. At the bottom of the chamber 1, an opening 107 formed in the plate 4 can be employed for the introduction either of a third electrode holder or of a cup 106, said cup being traversed by a nozzle 108 which is connected to a source of fluid so as to produce a predetermined atmosphere within the interior of the excitation chamber.

The third electrode is rigidly fixed to the bottom electrode which is carried by the column 7 and is preferably supported by a clamp, the jaws of which are separated by means of a piston which is rigidly fixed to a moving rod and are closed by means of a restoring spring.

Adjustment and control of the position of the electrodes are carried out with strict accuracy by means of two projection systems located at right angles.

The assembly consisting of the clamp holder and its control system is readily demountable from the exterior of the enclosure while the clamp itself and the electrodes can be reached within the interior of said enclosure after opening of the door 9. The contacts or even the half clamps can then be changed so as to be adapted to electrodes of different shapes or dimensrons.

Cleaning of these components may be carried out as often as may be required, thereby making it possible to perform analyses on corrosive or hazardous samples without any potential danger of contamination of the following sample, of the drive mechanism or of the operator. Within the interior of the excitation chamber, the lining 11 is detachable and can consequently be readily decontaminated or replaced.

Similarly, the circulation system for cooling the clamp holder as well as the good insulation obtained by virtue of the presence of graphite contacts permits the use either of an electric are or of a high-voltage spark as may be required.

lt will readily be understood that a number of difierent modifications could be made in the embodiment which has just been described without thereby departing from the scope of the invention. For example, the opening of the clamp could be controlled in a different manner and in particular by means of a cable wound on a drum which is fitted with a restoring spring. The number of electrodes can also vary by reason of the fact that only one electrode is necessary, or the fact that the two plates 2 and 4 each support a column 7 and an electrode or alternatively the fact that an additional electrode is associated with either of these two electrodes.

What we claim is;

1. An electrode holder for an emission spectrograph, comprising a cylindrical excitation chamber having parallel top and bottom end walls a sliding column passing through at least one of the top and bottom end walls of the chamber, an electrode-holding clamp supported by said column within the interior of the chamber, a system for controlling the opening and closure of the clamp and the displacement of the column in three directions at right angles to each other mounted externally on said chamber, said clamp-carrying column comprising two coaxial tubes, one tube being stationary and the other being rotatable each of said tubes having an endpiece, a half clamp mounted on each of said endpieces, said system including a carriage block and two superposed and movable carriages supporting said column and rigidly fixed for translational motion in a first direction parallel to the end walls of said chamber, means for coupling said carriages for controlling the displacement of the upper carriage alone in a second direction at right angles to the first direction and parallel to the end wall of said chamber supporting said carriages, a nut rigidly fixed to said block mounted for translational motion in a direction perpendicular to said end walls only along a worm-screw, and means for rotating said worm-screw said worm-screw being carried by said upper carriage.

2. An electrode holder according to claim 1, including a plurality of connector pins for extending each half clamp inserted in corresponding recesses of the endpiece.

3. An electrode holder according to claim 1, wherein the end wall of the chamber has an opening through which the column passes, a ring closing said opening in leaktight manner said column being slidably fitted in said ring and said ring sliding laterally within a recess formed in said end wall.

4. An electrode holder according to claim 1, wherein the bottom end wall of the chamber is adapted to support a cup traversed by a nozzle for the admission of a fluid which constitutes the atmosphere within the interior of said chamber.

5. An electrode holder according to claim 1, wherein the chamber is provided with a removable lining of black plastic material.

3 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,619,062 Dated November 9, 1971 n en fl Alain Heres and Alfred Simenauer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

rm On the front page between data element identifiers [45] and [32] insert [73] assignee Commissariat A L'Energie Atomique, Paris, France--.

Signed and sealed this 11 th day of April 1972.

(SEAL) Attest:

EDWARD M.FLILTCIIER, JR, ROBERT GOTTSCHALK Attosting Officer Commissioner of Patents 

1. An electrode holder for an emission spectrograph, comprising a cylindrical excitation chamber having parallel top and bottom end walls a sliding column passing through at least one of the top and bottom end walls of the chamber, an electrode-holding clamp supported by said column within the interior of the chamber, a system for controlling the opening and closure of the clamp and the displacement of the column in three directions at right angles to each other mounted externally on said chamber, said clamp-carrying column comprising two coaxial tubes, one tube being stationary and the other being rotatable each of said tubes having an endpiece, a half clamp mounted on each of said endpieces, said system including a carriage block and two superposed and movable carriages supporting said column and rigidly fixed for translational motion in a first direction parallel to the end walls of said chamber, means for coupling said carriages for controlling the displacement of the upper carriage alone in a second direction at right angles to the first direction and parallel to the end wall of said chamber supporting said carriages, a nut rigidly fixed to said block mounted for translational motion in a direction perpendicular to said end walls only along a worm-screw, and means for rotating said wormscrew said worm-screw being carried by said upper carriage.
 2. An electrode holder according to claim 1, including a plurality of connector pins for extending each half clamp inserted in corresponding recesses of the endpiece.
 3. An electrode holder according to claim 1, wherein the end wall of the chamber has an opening through which the column passes, a ring closing said opening in leaktight manner said column being slidably fitted in said ring and said ring sliding laterally within a recess formed in said end wall.
 4. An electrode holder according to claim 1, wherein the bottom end wall of the chamber is adapted to support a cup traversed by a nozzle for the admission of a fluid which constitutes the atmosphere within the interior of said chamber.
 5. An electrode holder according to claim 1, wherein the chamber is provided with a removable lining of black plastic material. 